Stabilized well drilling bit



Sept. 15, 1936. 1 c, wR|GHT 2,054,277

STABILIZED WELL DRILLING BIT Filed July 24, 1933 2 Sheets-Sheet l &

Affa/wey Sept. 15, 1936.

J. c. WRIGHT STABILIZED WELL DRILLING BIT Filed July 24, 1933 2 Sheets-Sheet 2 /n V60 for Jesse C. Wrf'g/vf Afforney Patented Sept. 15, 1936 UNITED STATES PATENT OFFICE STABILIZED WELL DRILLING BIT Application July 24, 1933, Serial No. 681,909

2 Claims.

This invention relates to a well drilling tool and relates more particularly to a core receiving well drilling bit. It is a general object of this invention to provide a simple, practical and effective core receiving well drilling bit that is operable to drill a straight vertical bore.

Another object of the invention is to provide a well drilling bit having an annular pilot bit operable to make a comparatively narrow annular cut in the earth formation, and cutters spaced a considerable distance above the pilot bit that are operable to ream the well bore to a diameter large enough to provide for the safe passage of the core receiving body of the tool.

Another object of the invention is to provide a core receiving well bit including reaming cutters spaced above the pilot bit that have blunt outer or peripheral surfaces that are comparatively large in area that operate to effectively guide the drill to make a straight vertical bore.

Another object of the invention is to provide a core receiving drill that is operable to take or obtain a core of maximum diameter and to maintain the full diameter of the well bore.

Another object of the invention is to provide a well drilling tool including a long tubular pilot cutter having a bit on its lower end for making a narrow annular cut, bearing pads or projections spaced longitudinally on the pilot cutter for engaging the walls of said narrow cut to guide the drill to make a straight vertical hole, and cutters on the core receiving body of the tool to cut the bore to size.

Another object of the invention is to provide a well drilling bit comprising an annular pilot cutter for making an annular core forming cut in the earth formation, and roller reaming cutters spaced above the pilot cutter for reaming the bore to provide for the free passage of the core receiving body of the tool through the well bore and to stabilize the tool during operation.

It is another object of the invention to provide a well drilling tool of the character mentioned in which the reaming roller cutters are rotatable on inclined axes so as to have large peripheral areas in cutting or reaming engagement with the earth formation to effectively guide and stabilize the tool and to ream the well bore to size.

It is a further object of the invention to provide a core receiving well drilling tool that is rapid and efficient in operation and that is simple and inexpensive of manufacture.

The various other objects and features of the invention will be best and fully understood from the following detailed description of typical forms and applications of the invention, throughout which description reference is had to the accompanying drawings, in which:

Fig. 1 is a side elevation of one embodiment of the invention operating within a well bore illustrating certain parts broken away to appear in vertical cross section. Fig. 2 is a transverse detailed sectional view taken as indicated by line 22 on Fig. 1. Fig. 3 is a side elevation and partial verticalsection of another form of the invention. Fig. 4 is a fragmentary diagrammatic view illustrating the manner of operation of one of the reaming roller cutters-illustrated in Fig. 3. Fig. 5 is a partial side elevation and vertical section of the lower portion of still another form of the invention, and Fig. 6 is an enlarged detailed sectional view taken as indicated by line 6-6 on Fig. 5.

The form of the invention illustrated in Figs. 1 and 2 of the drawings, includes, generally, a barrel or tubular body Ill, an annular pilot bit II on the lower end of the body Ill, and reaming and stabilizing cutters l2 spaced above the pilot bit II.

The barrel or body I0 is a tubular structure adapted to be attached to the lower end of a drilling string. The body It) includes an elongate barrel proper l3, adapted to receive the core cut by the pilot bit I I. A suitable adaptor sub l 4 may be provided on the upper end of the barrel l3 to facilitate its connection with the lower end of the drilling string. In accordance with the invention, the barrel I3 is comparatively large in diameter, and is of considerable length so that it is adapted to receive a long core of large diameter. A sub is provided on the lower end of the barrel l3 and has a downwardly projecting threaded pin it. A core catcher sub I1 is screwthreaded on the pin 16. The core catcher sub I1 is a tubular member having a central longitudinal opening i8 adapted to freely pass or receive the core C. A screw threaded pin I9 is provided on the lower end of the core catcher sub l1.

Suitable core catching means is provided on the sub ll to engage the core C when the drill is to be withdrawn from the well to break the core loose from the formation and to support the core in the drill while it is pulled from the well bore. In the particular construction illustrated in the drawings, there is a plurality of core gripping dogs provided to grip and hold the core C. The core engaging dogs 20 have their outer ends pivoted in recesses 2| in the interior of the sub ll. The inner ends of the dogs 20 are sharpened and project into the opening l8 so as to engage the drill.

the core. During the drilling operation, the core catching dogs 20 are forced to upwardly and inwardly inclined positions as illustrated in Fig. 1 of the drawings by the core C as it is received in Springs 22 are provided to normally yieldingly urge the active ends of the dogs 20 inwardly and downwardly to cooperate with the core.

The pilot bit II constitutes the lower section of a cutter head or bit head comprising an upper section 25 and the lower section or pilot bit II. The upper section 25 of the bit head is screwthreaded on to the pin I9 of the core catcher sub and carries the reaming and stabilizing cutters I2, as will be hereinafter described. The pilot bit II is an elongate tubular member having a central longitudinal opening 26 of substantially the same diameter as the opening I8 of the core catcher sub IT. The upper end portion of the pilot bit I I is screw threaded into a socket 21 in the upper section 25 of the bit head. Cutting parts 28 are provided on the lower end of the pilot bit II. The pilot bit II is preferably of considerable length so that the cutting parts 28 are spaced a substantial distance below the reaming cutters I2 carried by the upper section 25 of the bit head. The cutting parts 28 are in the nature of blades or teeth projecting downwardly from the lower end of the pilot bit I I. There may be any suitable number of circumferentially spaced cutting teeth or parts 28. In accordance with the invention, the cutting parts 28 project from both the exterior and interior of the pilot bit II to provide for the free, safe passage of the pilot bit into the annular out A made in the formation by the cutting parts. The cutting teeth or cutting parts 28 have sharpened lower edges 29 for acting on the formation during the operation of the drill to make the annular cut A.

The outer edges or faces 38 of the cutting parts 28 are blunt or comparatively wide so that they are adapted to cooperate with the outer wall of the annular out A to guide the bit and prevent it from taking a lateral or inclined course. As the tool or drill is rotated during operation, the cutting parts 28 make the annular out A in the earth formation to form the core 0 which is received in the opening 26 of the pilot bit, the opening I8 of the bit head sub I1, and finally by the barrel I3. In accordance with the rotary method of well drilling, rotary mud or circulation fluid is passed downwardly through the drilling string under pressure and is discharged at the bottom of the well bore to prevent the drilling tool from sticking or freezing in the bore and to carry away the cuttings. In the tool provided by the present invention, the circulation fluid passes downwardly through the barrel I3, sub I1, and pilot bit I I to discharge from the lower end of the pilot bit into the annular cut made by the cutting parts 28. As described above, the cutting parts 28 project inwardly from the lower end of the pilot bit II so that suitable clearance is provided around the core C for the downwardly flowing circulation fluid. The circulation fluid in passing downwardly around the core 0 maintains the core loose and free in the tool and effectively flushes the cutting parts 28 and pilot bit I I so that the pilot bit cannot freeze in the comparatively narrow annular out A. After issuing from the lower end of the pilot bit II, the rotary mud or circulation fluid passes upwardly out of the annular out A to flush the reaming cutters I2 and to maintain suitable turbulence and circulation in the well.

The stabilizing and reaming cutters I2 are carried by the upper section 25 of the bit head and are operable to enlarge the well bore and to stabilize and guide the drill. The upper section 25 of the bit head is comparatively heavy having thick Walls, and the cutters I2 are in the nature of teeth or blades projecting outwardly from the lower end of the section 25. There may be any suitable number of cireumferentially spaced cutters I2 provided on the section 25. In the particular form of the invention illustrated in the drawings, there are four substantially equally spaced cutters I2.formed integral with the section 25. The forward faces 3I of the cutters I2 are substantially radial relative to the axis of rotation of the drill but are slightly inclined downwardly and forwardly. The lower ends of the cutters I2 are bevelled away at their rear sides to provide sharp cutting edges 32. The cutting edges 32 may be straight and substantially normal to the vertical axis of the tool. The lower portions of the outer or peripheral ends of the cutters I2 may be bevelled at their rear sides to have sharp vertical cutting edges 33. It is a feature of the present invention that the reaming and stabilizing cutters I2 have large faces or surfaces at their outer edges to limit or prevent lateral movement of the drill and thus stabilize the drill and insure the drilling of a straight vertical well bore. The upper portions 34 of the outer edges of the cutters I2 are blunt or unsharpened, being in the form of large plane surfaces. The outer stabilizing surfaces 34 of the cutters I2 may be curved concentric to the vertical axis of rotation of the drill. In the preferred construction, the guiding or stabilizing surfaces- 34 are of considerable length or vertical extent. The outer rear edges or corners 31 of the cutters I2 may be bevelled.

During operation, the lower cutting edges 32 and 33 of the reaming cutters I2 act on the formation at the upper end of the annular out A to materially enlarge the bore. The guiding or stabilizing surfaces 34 of the cutters I2 are adapted to engage the Walls of the well bore to prevent the cutters from penetrating laterally into the formation and thus guide the drill to make a vertical cut or bore.

It is believed that the operation of the drill illustrated in Figs. 1 and 2 of the drawings will be readily understood from the foregoing detailed description. The cutting parts 28 of the pilot bit I I are spaced a substantial distance below the cutters I2 and are efiicient in making the comparatively narrow annular channel or out A in the earth formation. The outer edges or surfaces 30 of the cutting parts 28 are unsharpened or blunt, and guide the pilot bit II to drill a straight hole. The cutters I2 are effective in reaming or enlarging the diameter of the well bore and their guiding or stabilizing surfaces 34 cooperate with the wall of the enlarged bore to guide the drill. It will be apparent how the vertically spaced series of spaced guiding surfaces 30 and 34 are particularly effective in stabilizing the drill, and in guiding it to make a straight bore. As the respective cuts made by the cutting parts 28 and cutters I2 are comparatively narrow, the drill is very eflicient and rapid in operation. It

is to be noted that the drill is capable of forming nular cut in the earth formation, an upper section 42, and roller reaming and stabilizing cutters 43 on the upper section 42.

The lower section 40 of the bit-head is an elongate tubular member having a central longitudinal opening 43 adapted to receive or pass the core cut by the cutting parts 4|. The section 40 is comparatively long and has an upper portion 44 of reduced external diameter. The cutting parts 4| are in the nature of blades or teeth projecting downwardly from the lower end of the section 40. The cutting parts 4| project from the exterior of the section 40 and extend inwardly at the lower end of the opening 43 to make an annular cut in the formation sufhciently wide to receive the section 40 and the lower portion of the section 42 with suitable clearance. The lower ends of the cutting parts 4| are provided with sharpened cutting edges 45. The outer edges 46 of the cutting parts 4| are blunt and comparatively wide so that they operate as bearing or guiding surfaces to cooperate with the wall of the annular cut to guide the lower end of the drill. The cutting edges 45 of the cutting parts 4| may be straight and normal to the axis of rotation of the drill.

The upper section 42 of the bit head is a tubular member having a central longitudinal opening 41 adapted to pass or receive the core formed by the cutting parts 4|. The upper section 42 is adapted to be attached to the body of the drill, for example it may be attached to the lower end of the core catcher sub II. A screw threaded socket 48 is provided in the upper end of the section 42 to receive the pin |9. A comparatively deep socket 49 is provided in the lower end of the section 42 to receive the reduced upper portion 44 of the section 40. The base or lower part of the portion 44 is screw threaded into the socket 49. Circumferentially spaced outwardly projecting lugs or parts 50 are provided on the upper section 42. Recesses are provided in the exterior of the section 42 at the lower ends of the parts 50. The recesses 5| extend upwardly and inwardly from the lower ends of the parts 50 and have upwardly and inwardly inclined side walls. The opposite ends of the recesses 5| are open to the well bore as clearly illustrated in Fig. 3 of the drawings.

The stabilizing and reaming roller cutters 43 are rotatable in the recesses 5| and project downwardly and outwardly from the lower ends of the recesses to act on the earth formation. The roller cutters 43 are substantially cylindrical in their general configuration and are provided with longitudinal extending peripheral cutting parts 52. The roller cutters 43 are each rotatable on twopiece shouldered bushings 53 carried by pins 54. The cutter carrying pins 54 are inclined upwardly and outwardly relative to the central longitudinal axis of the bit head being substantially normal to the inclined side walls of the recesses 5i. The outer ends of the sections of the bushings 53v are adapted to bear against the opposite inclined walls of the recesses 5|. Reduced eccentric lugs 60 are provided on the outer ends of the pins 54 and fit correspondingly shaped openings in the parts 50. The inner portions of the pins 54 are carried in openings 6| in the section 42 communicating with the upper end of the socket 49. The cutters 43 and pins 54 are adapted to be assembled on the section 42 prior to the connect on of the sections 40 and 42. The cutters 43 with their bushings 54 are positioned in the recesses 5|, and the pins 54 are inserted in the openings 6| and are passed through the bushings in the recesses so that their reduced eccentric lugs 60 are received in the openings in the parts 5!. Heads 62 are provided on the inner ends of the pins 54 and are adapted to be engaged 'by the upper end of the part 44 when the sections 40 and 42 are threaded together. It will be apparent how the part 44 threaded into the socket 49 dependably locks the pins 54 against displacement. The eccentric lugs 60 of the pins positively hold the pins against rotation. The roller cutters 43 project downwardly and outwardly from the open lower ends of the recesses 5| and are operable to act on the formation to enlarge the well bore and to steady the drill.

Fig. 4 of the drawings is a diagrammatic view illustrating the operation of one of the roller cutters 43. In Fig. 4 of the drawings, W'represents the wall of the well bore and X represents a peripheral surface of a roller cutter 43. Due to the pitch or inclination of the roller cutters 43 they have peripheral cutting portions of substantial circumferential extent in engagement with the wall W of the well bore. Y represents the line or area of contact between the cutter X and the wall W of the well bore. It will be seen that this contact of the several cutters 43 with the walls of the well effectively steadies or stabilizes the drill so that it has no tendency to wobble or drill a crooked hole. Further, the extensive engagement of the roller cutters 43 with the formation prevents the premature or excessive wearing away of portions of the cutting parts 52.

In the operation of the form of the invention illustrated in Fig. 3 of the drawings, the cutting parts 4| on the lower section 40 make a com paratively narrow annular cut in the formation that is sufiiciently wide to receive the section 40 with suitableclearance. The reaming roller cutters 43 engage the earth formation at the upper end of the cut made by the cutting parts 4| to materially enlarge the bore so that it may safely receive the core receiving body of the drill. The broad, blunt outer edges 46 of the plurality of cutting parts 4| and the extensive portions Y of the-cutters 43 in contact with the earth formation operate to guide the drill to make a straight vertical bore. The circulation fluid discharging downwardly through the bit head around the core effectively flushes the cutting parts 4| and roller cutters 43, and prevents freezing or sticking of the drill in the bore.

The form of bit heal or cutter head illustrated in Figs. 5 and 6 of the drawings includes, generally. a pilot cutter ill, bearing parts 1| on the pilot cutter and an upper cutter 12. The cutting head or bit head is adapted to be connected to the lower end of the body or barrel of a core receiving drill. for example, it may be attached to the sub I! described above. The pilot cutter 10, instead of being sectional as in the other forms of the invention, may be an integral tubular member comprising an upper portion 13 and a lower portion or main portion 14. The upper portion 73 is of enlarged external diameter and carries the upper cutter 12. The upper portion 13 is adapted to be attached to the sub l1 and is provided at its upper end with a socket 15 for receiving the threaded pin I!) of the sub. An external downwardly facing annular shoulder 16 is provided on the exterior of the upper portion 13.

In accordance with the form of the invention being described, the main lower portion 14 of the pilot cutter is long, in practice being five feet or more in length. The portion 14 is uniform in external and internal diameter throughout its length and its opening 11 is adapted to receive the core and allow it to pass upwardly into the barrel. Cutting parts are provided on the lower end of the portion 14 for making a comparatively narrow annular cut in the earth formation. A shoe I8 is screw threaded on the lower end of the portion H and carries cutting blades 19. The cutting parts or blades 19 project downwardly from the shoe 18 to engage the formation and cut or make the annular cut. The cutting blades 19 also project outwardly from the periphery of the shoe TB and inwardly from the interior of the shoe to make a cut sufilciently wide to pass or receive the portion 14 with suitable clearance. The core Z formed by the cutting blades 19 is received by the opening 11 with clearance. Reaming cutting blades 80 are provided on the shoe 18 to maintain the cut formed by the pilot cutter to its proper size. The reaming blades 80 maintain the cut to size without necessitating the provision of an excessive amount of cutting edge at the bottom of the cut or bore.

, The bearing parts H are provided on the exterior of the portion H to engage the wall of the annular channel or bore, formed by the cutting blades 19, to guide the cutter and prevent the cutter from drilling a crooked hole. The bearing parts H are in the nature of spaced projections on the main portion 14 of the pilot cutter. In the preferred construction, the bearing parts H are elongate and extend longitudinally of the portion 14. In accordance with the broader aspects of the invention, there may be any suitable number of bearing parts H grouped or arranged in any desired manner. In the particular case illustrated in the drawings, the bearing parts H are arranged or grouped in longitudinally spaced circumferential series, the bearing parts of each series being circumferentially spaced. The lowermost series of bearing parts H is preferably located adjacent the shoe l8 and the uppermost series of bearing parts is preferably positioned adjacent the upper cutter 12. The bearing parts H may be out of vertical or longitudinal alignment with the cutting blades 19 and 80. In accordance with the invention, the bearing parts H are of considerable width to present large bearing surfaces 8! to contact the outer wall of the annular cut. The bearing surfaces 8| of the parts H are concentrically curved about the longitudinal axis of the drill and have only very slight clearance with the external wall of the annular cut made by the pilot cutter, in fact the bearing parts H may very closely fit the bore made by the pilot cutter to accurately guide the drill to make a straight vertical bore. There is no danger of the drill becoming stuck or sanded in, for when the drill is raised to lift the portion 14 clear of the small bore made by the pilot cutter the drill is effectively freed. As the series of bearing parts H are spaced throughout the length of the long cutter portion 14 they are particularly effective in preventing deviation of the cutter from its ver tical course. It will be apparent how the bearing parts 1| spaced along the long cutter portion 14 effectively guide the pilot cutter and the drill to cut a straight vertical bore. The circumferential spacing of the bearing parts H allows the free upward circulation or flow of the circulation fluid and cuttings.

The upper cutter 12 is carried on the portion 13 to enlarge the bore or cut the bore to size. As the portion 13 is attached to the sub H, the

tool with suitable. clearance.

cutter 12 is disposed at the lower end of the main or core receiving body of the drill and operates to enlarge the well bore to freely pass or receive it with the required clearance. The cutter 12 includes an annular body or shoe 90 screw threaded on the portion 13. The upper end of the shoe 90 seats upwardly against the shoulder 16 so that the cutting pressures are transmitted directly to the portion 13. A plurality of circumferentially spaced cutting parts 9| in the form of blades are provided on the shoe 90. The cutting blades 9| operate to make an annular cut in the earth formation at the upper end of the comparatively narrow channel or cut made by the blades 79. The blades 9| may be substantially radial and may be comparatively heavy. Cutting edges 92 are provided on the lower ends of 'the blades SI and are substantially normal to the vertical axis of the drill. The blades 9| are provided with vertical or reaming cutting edges 93 and the lower outer corners 94 of the blades 9| are cut away or bevelled so that the blades may be sharpened without forming thin, weak corners.

During operation of the form of the invention illustrated in Figs. and 6 of the drawings, the blades 19 operate to form a comparatively narrow annular channel in the earth formation far in advance of the cut made by the upper cutter 82. The bearing parts H on the long tubular portion 14 may engage the wallof the annular cut in the event that the drill has a tendency to deviate from the vertical, thereby guiding the cutter to make a straight vertical bore. As the series of bearing parts H are spaced longitudinally throughout the length of the portion 14 they are particularly effective in guiding the pilot cutter. The close fit of the bearing parts H in the small bore of the pilot bit effectively prevents deviation of the drill from its straight vertical course. It will be apparent that the close or accurate guiding of the pilot bit by means of the bearing parts insures the drilling of a straight vertical bore without causing the drill to become stuck in the bore. The circulation fluid flowing downwardly through the drill discharges at the shoe 18 to effectively flush the blades 19 and 80 and to provide suitable turbulence in the bottom of the cut or bore, preventing sticking or freezing of the pilot cutter. The circulation fluid is free to flow upwardly around the portion I4 between the circumferentlally spaced bearing parts H. The blades 9| of the upper cutter 12 cut the bore to the proper size to receive the body of the The blades 8| are washed or flushed by the circulation fluid flowing upwardly from the upper end of the narrow channel made by the pilot cutter. The drill head or cutter head illustrated in Figs. 5 and 6 of the drawings involving the long pilot cutter forming the narrow annular channel and carrying the bearing and guiding projections H is particularly effective in rapidly drilling a straight vertical bore and in receiving a large unbroken core.

Having described only a typical form and application of my invention, I do not wish to be limited or restricted to the specific forms and applications herein set forth, but wish to reserve to myself any modifications or variations that may appear to those skilled in the art, or fall within the scope of the following claims.

Having described my invention, I claim:

1. A cutter head for a core receiving drill ineluding a tubular body having a downwardly facing shoulder and a lower portion of substantial length extending downwardly from said shoulder, cutting parts on the lower end of said portion for making an annular cut in the formation, longitudinally and circumferentially spaced bearing parts on the said portion for engaging the wall of said cut, a member threaded on said portion and bearing upwardly against the shoulder, and cutting parts on the member for enlarging the bore.

2. A cutter head for a core receiving drill including a tubular body having a downwardly facing shoulder and a lower portion of substantial length extending downwardly from said shoulder, cutting parts on the lower end of said portion for making an annular cut in the formation, spaced longitudinally disposed bearing parts on said portion for engaging the wall of said out, a shoe threaded on said portion to bear upwardly against the shoulder, cutting parts on the shoe for enlarging the bore, and means at the upper end of the body for connecting with the drill.

JESSE C. WRIGHT. 

